1. Field of Invention
The present invention relates to an integrated generation control system and, more particularly, to an integrated generation control system for enhancing the dynamic stability of a generation system or the stability of the output from generators operated in parallel.
2. Related Prior Art
An automatic voltage regulator (“AVR”) is used to control an excitation system of a synchronous generator. The excitation system is used as a DC power supply for the field windings of the synchronous generator. Within the operative capacity of the synchronous generator, the filed currents of the field windings are used to control the voltage output from the synchronous generator and the ineffective power flow. However, the damping torque of the synchronous generator is inevitably reduced by the AVR in operation. Hence, it is necessary to provide a stabilizer to provide an additional control signal to produce a positive damping torque to compensate the reduction of the damping torque for the use of the AVR. To increase the quick responses and transient changes of the voltage output from the synchronous generator, the gain is increased in the AVR. In operation, the stabilizer adjusts the transfer function of the synchronous generator and moves the limits of the transfer function to control the root locus of the synchronous generator in the half plane and expedite the attenuation of the power oscillation. Hence, there would not be any unstable oscillation and the stability of the synchronous generator is increased whatever the transient changes or responses might be.
The excitation system may be a DC, AC or static one. The stabilizer may be operated in a two-mode input model, one-mode input model or multi-band model.
A conventional analog AVR is equipped with a control card that is a single element without a backup structure. In the analog AVR, the signal is transferred by wires and processed by analog elements such as amplifiers, adders, subtracters and/or comparators. The inevitable aging of any of the analog elements would cause precision drift and the precision of the transfer of the signal would be reduced. It is difficult to correct such errors and maintain the analog AVR.
A digital AVR measures and converts an analog signal to digital signal and transfers the digital signal to a microprocessor that executes calculation on the digital signal in accordance with an algorithm. The result from the calculation may be released in a digital form or released after it is converted to an analog form. The digital AVR needs a more complicated circuit than the analog AVR. However, regarding the transfer of the signal, the digital AVR is more precise and less vulnerable to the aging than the analog AVR because the digital AVR is equipped with a checking mechanism based on check codes.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art.